In a high-frequency package, in which high-frequency circuits are mounted that operate in high-frequency bands such as millimeter wave bands, the high-frequency circuits are mounted in a cavity that is electrically shielded using a seal ring, a lid and the like, taking airtightness for weather resistance, operating stability and the EMI (radioactive spurious) standard into consideration.
In Patent Document 1, a semiconductor chip and a circuit substrate are mounted in an outer case. In order to establish a connection with a waveguide disposed on the downside of the circuit substrate and the outer case, a dielectric window having a stripline antenna formed thereon is disposed immediately above the waveguide. The stripline antenna is connected to the circuit substrate via a stripline so that the waveguide disposed below the dielectric window is connected thereto. The upside opening of the outer case is sealed with a lid in an airtight manner.